Sony Xperia Z has a 5″ 1080p display, featuring an incredibly high pixel density of 441 ppi. In order to power such a screen, the device features a 1.5 GHz quad-core Qualcomm Snapdragon S4 Pro processor, backed by the speedy Adreno 320 GPU. The Xperia Z also features 2 GB of RAM, 16 GB of internal storage, and a microSD card slot capable of taking up to 32 GB cards.
Xperia Z will not receive official Marshmallow support but there are plenty of custom ROMs using which you can update Xperia Z to Android 6.0.1. An unofficial version of CM 13 is available for Xperia Z. It is still in alpha stage but it can be used for day to day purposes. A detailed guide is given below.